code: def test_op_works_when_no_pipeline_is_specified(self) -> None:
      pipeline = DataPipeline.sample([]).and_return()
  
      for _ in range(2):
          with pytest.raises(StopIteration):
              next(iter(pipeline))
  
          pipeline.reset()
  
file_path: fairseq2/tests/unit/data/data_pipeline/test_sample.py
imports: import math
  import pytest
  import torch
  from fairseq2.data import DataPipeline, DataPipelineError, read_sequence
  from fairseq2.data.text import read_text
  from fairseq2.typing import CPU
  from tests.common import tmp_rng_seed
label_desc: Use image node_id 4 for calling the TestSampleOp obj's underlying member method code with example usage: obj.test_op_works_when_no_pipeline_is_specified() without return types